Apparatuses for pre-punching (pre-drilling) holes for introducing foundation devices and for introducing the foundation devices themselves into the ground are known. In the simplest case, they are maneuvered by the operator into the position in which pre-punching (pre-drilling) is to take place or the foundation devices are to be set.
There are special requirements when groups of foundation devices are to be set, for example rows with consistent spacing. Here, in the simplest case, the operator orients himself with respect to a specified boundary line, for example—when setting foundation devices for road boundary posts—with respect to the edge of the carriageway, wherein the determination of the required, defined, more or less consistent spacing requires an additional measurement. In doing so, in case of doubt, the person entrusted with measuring the spacing will mark the measured positions in preparation for the subsequent working steps.
If there are no such guides—in open country for example—they can be replaced by other aids, for example by establishing orientation lines and points using theodolites. However, this requires significant effort, particularly when not only single rows of foundation devices but whole fields are to be set, such as frequently occurs today, for example, when installing photovoltaic systems in open country.
Theoretically, here too the positions of the (possibly hundreds of) foundations can be measured individually. However, the effort required for this is immense. In addition, the support for such systems requires a precision and in particular an accuracy of positioning of the foundations which can only be maintained with difficulty using conventional measuring methods.
This may still be feasible when such a system is to be erected in flat terrain, as the foundations are then to be positioned on a rectangular grid which is still relatively easy to measure on a flat surface.
However, this becomes considerably more difficult when the support is to be installed in uneven terrain, such as is increasingly required today in light of the amount of land taken up by such systems. This is because, under certain circumstances, the positions of the foundations then stray from the rectangular grid and instead are relocated—depending on the slope of the terrain—to a more or less pronounced, irregular diamond pattern, such as that which the applicant has made the subject of its application DE 10 2010 005 098.9.
This means that, in such a case, every single foundation position actually has to be calculated and individually measured based on a recorded terrain profile.
Here, the calculation of the foundation positions based on a terrain profile using a suitable electronic data processing program presents no problems in itself. In this regard, reference can also be made to the applicant's own application previously mentioned. However, the measurement of the calculated positions in the terrain is extremely laborious and subject to error.
Today, this is usually carried out with the help of a satellite-controlled plumb rod, which the operator has to position at the indicated point on the ground.
However, inaccuracies, which are perpetuated when the located positions are then marked—for example with the help of a hammered-in peg—, occur even with this method. Further sources of error are added when the peg is then removed for pre-punching (pre-drilling) the hole for the foundation, and the pre-punching (pre-drilling) apparatus and/or the foundation to be introduced are positioned more or less precisely.
All in all, this can lead to deviations which far exceed the acceptable tolerances for erecting such systems.